Electric motors employed in environments that demand a fail safe source of motive power to be available even when there are present such faults in the motor windings as open circuit, short circuit and ground, have heretofore been unknown. The term fail safe as employed here is defined as being present when there are multiple redundant sources of motive power that are automatically present when one of the sources of motive power is lost for any reason.
Multiple redundant electromotive power sources in the form of multiple electric motors connected to drive a load in such a manner that the failure of one motor would leave a remaining motor or motors to drive the load have long been known.
In certain environments where space and weight considerations dictate the use of a single motor, multiple redundant electromotive power sources are simply prohibited. In this type of situation highly expensive finely crafted electric motors have been called into use in the hope of providing a sufficiently durable motor that was proven to have a high mean time between failures. Even with the most expensive motors, there is always the possibility of a fault arising in respect of one of the motor windings with the attendant loss of motive power. The invention to be described hereinafter by means of a novel multiple stator winding construction in conjunction with multiple power input channels provides a simple stator/rotor arrangement that creates a multiply redundant source of electromotive power.
There exists a number of commercial, aerospace and military environments where it is highly desirable to have multiple power channels electrically isolated, one from the other, which power channels are coupled to the same or separate loads. In the past, the simplest manner to accomplish this end would be to utilize a number of separate generators, each delivering power over a separate power channel to the same or separate loads.
In the situation where power is delivered to the same load over separate power channels from separate generators, there is inherently present the security of a redundant power supply to compensate for the possible occurrence of a fault arising in a winding of one of the generators with the attendant loss of power from the generator with the faulty winding. Where separate loads are powered by a single generator, the concern most generally has been that the characteristics of the load powered by the generator will be reflected electrically back into the generator which may affect the output to another load in a manner that is not acceptable. In the past, the solution to this problem of the load characteristics being reflected electrically back into the generator has been answered by utilizing separate generators connected to separate loads, or the addition of complex circuitry to ensure the isolation of one load from another where a common generator was employed.
The invention to be described hereinafter provides for a stator winding arrangement in a generator that allows multi-power channel operation with electrical and magnetic isolation between channels.